Ocular motor measures in migraine with and without aura

Reflexive and Intentional Saccadic Eye Movements in Migraineurs

Background: Migraine has been postulated to lead to structural and functional changes of different cortical and subcortical areas, including the frontal lobe, the brainstem, and cerebellum. The (sub-)clinical impact of these changes is a matter of debate. The spectrum of possible clinical differences include domains such as cognition but also coordination. The present study investigated the oculomotor performance of patients with migraine with and without aura compared to control subjects without migraine in reflexive saccades, but also in intentional saccades, which involve cerebellar as well as cortical networks.

Methods: In 18 patients with migraine with aura and 21 patients with migraine without aura saccadic eye movements were recorded in two reflexive (gap, overlap) and two intentional (anti, memory) paradigms and compared to 25 controls without migraine.

Results: The main finding of the study was an increase of saccade latency in patients with and without aura compared to the control group solely in the anti-task. No deficits were found in the execution of reflexive saccades.

Conclusions: Our results suggest a specific deficit in the generation of correct anti-saccades, such as vector inversion. Such processes are considered to need cortical networks to be executed correctly. The parietal cortex has been suggested to be involved in vector inversion processes but is not commonly described to be altered in migraine patients. It could be discussed that the cerebellum, which is recently thought to be involved in the pathophysiology of migraine, might be involved in distinct processes such as spatial re-mapping through known interconnections with parietal and frontal cortical areas.

Relationship of the Lateral Rectus Muscle, the Supraorbital Nerve, and Binocular Coordination with Episodic Tension-Type Headaches Frequently Associated with Visual Effort

Objective

To study the relationship between tension-type headaches and the oculomotor system in terms of binocular coordination, mechanosensitivity of the supraorbital nerve, and myofascial trigger points in the lateral rectus muscle, assessing the influence of visual effort caused by using a computer at work.

Design

Observational study with blind evaluation of the response variable.

Methods

Two groups were compared: 19 subjects with tension-type headaches and 16 healthy subjects, both exposed to computer use at work. A blinded assessor conducted three tests: measurement of the supraorbital nerve pressure pain threshold using a pressure algometer, evaluation of myofascial trigger points of the lateral rectus using the verbal numerical scale, and assessment of binocular coordination in smooth pursuit eye movements using an innovative video-oculography system. Tests were performed before work began and four hours later, and subjects in the headache group were examined when they presented a headache score of less than or equal to 3 on the verbal numerical scale.

Results

The headache group presented a greater sensitivity of the supraorbital nerve and greater local and referred pain of the lateral rectus ( P  < 0.05). Visual effort caused a significant worsening of these variables in both groups. However, binocular coordination after visual effort was only significantly affected in the headache group ( P  < 0.05), primarily in horizontal movements.

Conclusions

The finding of a higher alteration of the sensitivity of the supraorbital nerve, the myofascial trigger points of the lateral rectus, binocular coordination, and the significant influence of visual effort in patients with tension-type headaches suggest a new clinical perspective for problems related to tension-type headaches.

Vestibular migraine

During the last decades a new vestibular syndrome has emerged that is now termed vestibular migraine (VM). The main body of evidence for VM is provided by epidemiologic data demonstrating a strong association between migraine and vestibular symptoms. Today, VM is recognized as one of the most common causes of episodic vertigo. The clinical presentation of VM is heterogeneous in terms of vestibular symptoms, duration of episodes, and association with migrainous accompaniments. Similar to migraine, there is no clinical or laboratory confirmation for VM and the diagnosis relies on the history and the exclusion of other disorders. Recently, diagnostic criteria for VM have been elaborated jointly by the International Headache Society and the Bárány Society. Clinical examination of patients with acute VM has clarified that the vast majority of patients with VM suffer from central vestibular dysfunction. Findings in the interval may yield mild signs of damage to both the central vestibular and ocular motor system and to the inner ear. These interictal clinical signs are not specific to VM but can be also observed in migraineurs without a history of vestibular symptoms. How migraine affects the vestibular system is still a matter of speculation. In the absence of high-quality therapeutic trials, treatment is targeted at the underlying migraine.

Interhemispheric differences of fMRI responses to visual stimuli in patients with side-fixed migraine aura

Migraine sufferers with aura often report photosensitivity and visual discomfort outside of attacks and many consider bright or flickering light an attack-precipitating factor. The nature of this visual hypersensitivity and its relation to the underlying pathophysiology of the migraine aura is unknown. Using fMRI measurements during visual stimulation we examined the visual cortical responsiveness of patients with migraine with aura. We applied a within-patient design by assessing functional interhemispheric differences in patients consistently experiencing visual aura in the same visual hemifield. We recruited 20 patients with frequent side-fixed visual aura attacks (≥90% of auras occurring in the same visual hemifield) and 20 age and sex matched healthy controls and compared the fMRI blood oxygenation level dependent (BOLD) responses to visual stimulation between symptomatic and asymptomatic hemispheres during the interictal phase and between migraine patients and controls. BOLD responses were selectively increased in the symptomatic hemispheres. This was found in the inferior parietal lobule (P = 0.002), the inferior frontal gyrus (P = 0.003), and the superior parietal lobule (P = 0.017). The affected cortical areas comprise a visually driven functional network involved in oculomotor control, guidance of movement, motion perception, visual attention, and visual spatial memory. The patients also had significantly increased response in the same cortical areas when compared to controls (P < 0.05). We discovered a lateralized alteration of a visually driven functional network in patients with side-fixed aura. These findings suggest a hyperexcitability of the visual system in the interictal phase of migraine with visual aura.

Saccade behaviour in migraine patients

BACKGROUND

Voxel-based morphometry studies in migraine patients showed significant grey matter volume reduction in regions involved in the control of saccadic eye movements. We hypothesized that these changes would be reflected in dysfunctional saccadic behaviour.

METHODS

Saccades were recorded by infrared oculography using three different paradigms (pro-saccade with gap, pro-saccade overlap and anti-saccade with gap). We compared the results for migraine patients (n = 80) with those for controls (n = 87).

RESULTS

No significant differences were found between migraine patients with (n = 46) and without (n = 34) aura. Migraine patients showed a saccadic behaviour that differed from controls in three respects. In migraine patients, the latencies in the pro-saccade with gap paradigm were borderline significantly longer. Moreover, in both the pro-saccade with gap and the pro-saccade overlap paradigm we observed a larger intra-individual variation of the latency in migraine patients. However, the biggest difference was that the patients who received migraine prophylactic therapy made significantly more anti-saccade errors in the anti-saccade with gap paradigm, suggesting that inhibitory saccade control is impaired in migraine patients depending on the severity of the migraine.

CONCLUSION

We suggest a deficient inhibitory control, reflecting an executive dysfunction in the dorsolateral prefrontal cortex or a dysfunction in the cingulate cortex, is present in migraine patients.

Asymmetry of visual function in migraine with aura: Correlation with lateralisation of headache and aura

Background: Asymmetry of visual phenomena and headache is an important feature of migraine with aura.

Methods: This asymmetry was explored by assessment of visual illusions, hemifield spatial contrast detection (HCD) and hemifield pattern reversal visual evoked potentials (HVEPs) in 47 migraineurs with aura (MA), who were not taking prophylactic medications, and 62 controls with the same age range (16–59).

Results: Illusions were greater and HCD was poorer in MA than in controls. There were no group differences with respect to P100 amplitude. The longer the duration of migraine the poorer the HCD. When the aura was consistently unilateral it was associated with greater illusions, reduced HCD and reduced hemifield P100 amplitude. These findings were not related to the side of headache.

Conclusion: The lateralised changes suggest that the visual dysfunction occurs at a cortical level, and the correlation with the side of the aura suggests that dysfunction is most likely to occur in an area of preexisting anomaly of neural function.